Cylinder valves for internal combustion engines are generally opened and closed to allow for the intake and exhaust of gases in cylinders of internal combustion engines. Cylinder valves are generally operated by various valve lifter mechanisms including rocker arms and roller finger follower assemblies. The timing of the opening and closing of a cylinder valve (relative to the phase of crankshaft) is important to maximize fuel efficiency, assure complete combustion, and maximize engine output. Adjusting valve timing can lead to improvements in fuel economy, engine emissions, torque and idle quality.
Many different approaches have been proposed for providing adjustable valve timing. Some prior art approaches include independent lifter control for each cylinder by means of electrical solenoids or by changing the pivot point for a rocker arm. Various other approaches have also been proposed. Currently known approaches and assemblies for varying the timing of the valve event are either complex (and thus expensive) and/or are not well-suited for certain engine types, such as small internal combustion engines utilized in lawn mowers and other appliances.
Thus, there is a need for a variable valve timing apparatus, and engine incorporating the same, that provides for variable valve timing that is simple, cost-effective to manufacture and/or compact.